Storage media suitable for storing vast amounts of information content include streaming tape cartridges. Streaming tape drives are used to transfer multiple blocks of user data to and from the tape cartridges in a single streaming operation, rather than as a series of start-stop operations. Streaming tape is particularly well suited for backup operations as well as for providing archival and retrieval operations for vast quantities of information.
For even greater storage capacity, one or more tape drives and multiple tape cartridges can be positioned within a tape library. To manage such a vast amount of information, a central cartridge inventory can be maintained by a library controller within the library, so that logical requests for a particular drive and cartridge may be translated by the library controller into physical device locations and electromechanical operations, for example. A robotic arm can be elevated and rotated to a particular cartridge storage slot in order to move the cartridge from the slot and into a loading tray of the selected tape drive. The drive can then load the cartridge and thread the tape for recording/playback operations, following initial setup and calibration routines conventional with tape drives. The drive may be one of several drives within the library accessible by the robotic arm.
In addition, two or more libraries can, in effect, be linked using either a shared transport assembly or a progressive transport assembly. The shared transport assembly is a single transport mechanism that extends between multiple libraries to allow a cartridge to be passed from one library through to another library. The progressive transport assembly involves multiple robotic mechanisms, with a first robotic mechanism passing a cartridge from a first library to a second library, and a second robotic mechanism then passes the cartridge to a third library, etc., until the cartridge reaches its final destination.
One drawback of these types of libraries is the time delay incurred between receiving the tape cartridge request and having the cartridge ready for user data operations at the selected tape drive. Another drawback of this prior approach is that a single robotic arm mechanism services hundreds, if not thousands, of tape cartridge slot locations, and any failure of any of the robotic arm mechanisms essentially can interrupt or completely cease operation of the entire system. Further, this prior approach can limit scalability to the extent of selectively filling up the available tape cartridge slots with similar tape cartridges, or alternatively, with the cumbersome addition of similar tape libraries.
Each added library can also require relatively complex and costly reconfiguring of the entire library system. In addition to intricate mechanical and electrical coupling of the new libraries to existing libraries, physical space limitations may also be a concern. Further, physically linking libraries can impose certain proximity requirements on the actual positioning of the libraries relative to one another. Moreover, this type of linked library system can significantly increase the time-to-data, thereby reducing productivity and efficiency. Additionally, as new types of libraries continue to be developed and manufactured, linkage between older libraries and these modernized libraries can present serious compatibility and/or logistical challenges.